Measurement of serological and neutralizing antibodies specific to SARS-CoV-2 virus in humans with COVID-19 disease

Published

March 8, 2021

Author(s)

Linhua Tian, Elzafir B. Elsheikh, Paul Patrone, Anthony Kearsley, adolfas Gaigalas, Sarah L. Inwood, Sheng Lin-Gibson, Dominic Esposito, Lili Wang

Abstract

The global response to COVID-19 has led to rapid advances in diagnostic, surveillance, and vaccine development. Critical measurements underpinning many of these efforts include serological assays to assess seroprevalence of populations and the complex humoral immune responses to SARS-CoV-2, the coronavirus that causes COVID-19, as well as various vaccines. There is a clear and pressing need for improved assays to avoid costly diagnostic errors and ill-informed public health decisions. In the present study, we report the development of quantitative, multiplexed flow cytometry based serological and neutralization assays. The assay protocol defines the thresholds for IgG and IgM of both the full-length spike antigens and the receptor binding domain (RBD) of the spike antigen. Assay performance was evaluated using 10 blinded convalescent serum or plasma samples and demonstrated a specificity of 100%. Additionally, no correlative assay cross-reactivity were observed with the spike proteins of MERS, SARS1, OC43 and HKU1 viruses. Benchmarking against an RBD-specific SARS-CoV IgG reference standard, we demonstrated the quantification of anti-SARS-CoV-2 RBD antibody titer for ≈ 3 orders of magnitude concentration range (37.6 µg/mL to 31.0 ng/mL). We further demonstrated good correlation between anti-RBD antibody titers quantified by the serology assay and neutralizing antibody titers also obtained using a sensitive surrogate flow cytometry-based neutralization assay. Results from the suite of serology and neutralization assays help to improve measurement confidence, provides more holistic examination of patient samples, and are amenable to automation for high throughput measurements.

Citation

International Journal of Molecular Sciences

Pub Type

Journals

Citation

Tian, L. , Elsheikh, E. , Patrone, P. , Kearsley, A. , Gaigalas, A. , Inwood, S. , Lin-Gibson, S. , Esposito, D. and Wang, L. (2021), Measurement of serological and neutralizing antibodies specific to SARS-CoV-2 virus in humans with COVID-19 disease, International Journal of Molecular Sciences (Accessed April 24, 2025)